Problem: Simplify the following expression: $n = \dfrac{5r + 6}{4r + 7} \times 9$
Solution: When multiplying fractions, we multiply the numerators and the denominators. $n = \dfrac{(5r + 6) \times 9} {(4r + 7) \times 1}$ $n = \dfrac{45r + 54}{4r + 7}$